The court was closed for 10 minutes as the CCTV footage of the Thunder River Rapids Ride on October 26, 2016 was played at the inquest into the deaths of Cindy Low, Kate Goodchild, her brother Luke Dorsett and his partner Roozi Araghi.

Mr Foster said the footage ran for three or four minutes leading up to the incident.

He said it was "necessary for our purposes" to see the footage to put the incident in perspective to the evidence given at the inquest.

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Also on Thursday, the Queensland Coroners Court heard electricians at Dreamworld had repeatedly raised concerns about the jumble of wires inside the main control panel of the Thunder River Rapids Ride.

An expert's report following the tragedy described the wiring as a "rat's nest" and said it poised a real risk of serious malfunction.

The water levels dropped after a pump failed, leaving an empty raft stranded on rails on the conveyor belt. The next raft to come along hit it, and flipped, tipping four people into the conveyor belt mechanism. Picture: 9NEWS (9NEWS)

Park electrician Francoire De Villiers said the description was apt and he had understood the wiring was to be upgraded before the tragedy occurred.

"I notified (supervisor Scott) Ritchie every time we did preventative maintenance," he said.

Colleague Quentin Dennis told the inquest the wiring matter had been brought up with supervisors "multiple times".

Mr De Villiers, who had received a final written warning for a safety breach on the park's log ride weeks before the tragedy, had dealt with an earlier pump malfunction on the ride on the day of the fatal incident.

That was one of three separate pump failures he'd worked on in the five days before the tragedy.

The Thunder River Rapids ride. (aap)

A third failure of the south pump on October 25 contributed to the disaster, causing water levels to drop dramatically and a raft to become stuck on the ride's conveyor.

The raft containing the victims collided with the other raft and flipped into a vertical position, causing at least two of the victims to be flung into the machinery.

The inquest also heard from a former Dreamworld employee who described witnessing a similar incident in which four rafts collided on the ride over 15 years before the 2016 tragedy.

The inquest concludes tomorrow before being adjourned until a two-week period in October with a third two-week block now scheduled for November.